JP2023160788A - Installation for storing cryogenic fluid - Google Patents

Abstract

To inhibit generation of a cold pocket between a top of a tank and a surface of ground.SOLUTION: An installation for storing cryogenic fluid, in particular liquefied hydrogen, includes: a cryogenic tank (2) buried directly underground at a predetermined depth (P) below the surface of ground (3); and at least one heat transfer element (4) having a thermal conductivity greater than 10 W/m.K and buried in the ground with a first end situated between the tank (2) and the surface of the ground and a second end situated in a lateral zone around the tank (2).SELECTED DRAWING: Figure 1

Description

The present invention relates to equipment for storing cryogenic fluids.

The invention more particularly relates to an installation for storing cryogenic fluids, in particular liquid hydrogen, comprising a cryogenic tank buried underground at a predetermined depth directly below the earth's surface.

Currently, the majority of tanks in service stations for liquid fossil fuels (gasoline/diesel fuel) are buried in direct contact with the earth (ie directly buried).

For "alternative" fuels (natural gas, hydrogen), the solutions are currently not buried or remain contained in enclosures or vaults.

It has been observed that when such cryogenic tanks are buried directly in the ground, under certain conditions a cold pocket can form between the top of the tank and the ground surface.

This effect is the result of the combination of the presence of low temperatures around the tank and the presence of an insulating screen between the soil and the fluid coming from the surface of the tank. This cold pocket potentially represents a risk to people and equipment at the surface. In particular, this results in localized zones of frost or ice and equipment deterioration (e.g., in the latter case of freezing, the decomposition of civil engineering structures due to the generation of stresses brought about by the differential expansion of the ground). I might let you.

The aim of the invention is to overcome all or some of the drawbacks of the prior art mentioned above.

For this purpose, a device according to the invention or according to its generic definition given in the preamble above essentially provides that it has a power output of 10 W/m. K, and is buried in the ground with a first end located between the tank and the surface of the ground and a second end located in a lateral zone around the tank. characterized in that it comprises at least one heat-conducting element.

Additionally, embodiments of the invention may include one or more of the following features:
- the heat transfer element comprises at least one of a beam, a fluid pipe for a heat transfer fluid, a plate, a block, a fabric;
- Thermal conductive elements are made of the following materials: metals, alloys, aluminium, copper, steel (carbon steel), zinc, brass, nickel, iron, tin, bronze, carbon (in particular carbon or graphite or carbon fibers or carbon nanotubes) ),
- the second end of the at least one conductive element is located at a depth in the earth that is greater than the depth of the first end;
- the second end of the at least one conductive element is located at a depth corresponding to the depth of half the height of the tank;
- the tank is buried at a depth (P) between 50 cm and 10 m;
- the cryo-tank is of horizontal type, ie rectangular with a horizontal longitudinal axis, and the installation comprises at least one conductive element distributed along the longitudinal direction of the tank;

The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

Other specific features and advantages will become apparent from the following description provided with reference to the drawings.

The invention will be better understood on reading the following description, given by way of example only and with reference to the accompanying drawings, in which: FIG.

FIG. 1 is a schematic and partial diagram illustrating a possible exemplary embodiment of the invention.

The illustrated installation 1 for storing cryogenic fluids, in particular liquid hydrogen, comprises a buried cryogenic tank 2 . This cryogenic type tank is preferably configured to store cryogenic fluid at a temperature below 173K. This tank 2 is, for example, a double-walled tank, the inter-wall space of which is insulated under vacuum.

The tank 2 is directly buried underground by a predetermined depth P below the surface of the ground 3. The term "direct burial" refers to a burial without an enclosure or vault separating the tank from the soil (or sand and the like) in which it is buried. That is, the outer surface of the tank 2 can be in direct contact (or via an envelope, for example a flexible protective envelope) with the ground surrounding it.

For example, the tank 2 is buried to a depth P of between 50 cm and 10 m, for example between 1 m and 3 m.

According to one advantageous particular feature, the installation 1 has a power output of 10 W/m. has a thermal conductivity greater than K and has a first end located between the upper end of the tank 2 and the ground and a second end located in a separate zone around the tank 2. It comprises at least one heat transfer element 4 buried underground. For example, the second end is located at a depth corresponding to half the depth of the tank 2's height.

Preferably, the second end of the conductive element 4 is located at a deeper depth in the earth than the first end.

This configuration may be located between the top of the buried tank and the ground, using elements constructed of materials that have a greater thermal conductivity relative to that of the surrounding dry ground. Allowing low temperature dissipation from the zone.

This configuration reduces or eliminates the aforementioned drawbacks by equalizing the temperature range around the buried tank 2.

This allows direct burial with its advantages (footprint, cost, risk analysis, etc.).

The heat-conducting element 4 can be made of, for example, aluminum (thermal conductivity 200 W/m.K), copper (thermal conductivity 350 W/m.K), steel (thermal conductivity 50 W/m.K) or especially dry earth heat. It may be constructed of other materials having a higher conductivity (thermal conductivity on the order of 0.75 W/m.K).

In the illustrated example, the thermally conductive element comprises a plurality of beams 4 . More precisely, the installation 1 comprises a set of beams 4 made of a material with high thermal conductivity (aluminum, copper, etc.) buried in the upper part of the tank.

The cryotank 2 may be of horizontal type, ie cylindrical in shape, with a circular cross section and the longitudinal axis being horizontal.

The beams 4 are distributed along the longitudinal axis of the tank 2. As shown, the beam 4 can be arranged perpendicular to a tangent to the surface of the tank 2. In such an arrangement, the beam 4 may be perpendicular to the temperature line of the cold zone.

For example, these beams 4 may be longitudinally spaced apart by 5 cm to 200 cm. Their spacing is especially intended to allow the passage of water flow. Heat dissipation then occurs by simple thermal conduction, with the cold air from the upper pocket in the ground being discharged towards the hot zones on the sides around the tank 2.

These beams or bars 4 can have a square or circular or other solid or hollow cross section. These beams 4 may be placed in direct contact with the ground, for example to promote thermal contact during filling of the pit with sand. The length and/or cross-section and number of beams 4 can be dimensioned according to requirements.

Similarly, all or some of these beams 4 may be provided with branches in order to increase the exchange area between the ground and the conductive element.

Of course, the invention is not limited to this example. The beam 4 may therefore be replaced or supplemented with other heat transfer elements, such as heat transfer fluid circuits, solid or perforated plates, blocks, fabrics, etc.

For example, two blocks (or "layers") of thermally conductive material may be arranged similarly to the two rows of beams 4 illustrated (one conductive block on each side of tank 2). These blocks may be perforated to avoid water accumulation problems. Simple long enough fabrics can also be considered.

In this description detailed above, the embodiments mentioned are examples. Although the description refers to one or more embodiments, that does not imply that the features apply to only a single embodiment. Simple features of various embodiments may also be combined and/or interchanged to provide other embodiments.

Claims (7)

Equipment for storing cryogenic fluids, in particular liquid hydrogen, comprising a cryogenic tank (2) buried directly underground at a predetermined depth (P) below the surface of the ground (3),
10W/m. A heat transfer element (4) with a thermal conductivity greater than K, the first end of which is located between the tank (2) and the surface of the ground, the second end of which Installation, characterized in that it comprises at least one heat-conducting element (4) located in a lateral zone around ) and embedded in said ground. 2. Installation according to claim 1, characterized in that the heat transfer element (4) comprises at least one of a beam (4), a fluid pipe for a heat transfer fluid, a plate, a block, a fabric. The heat-conducting element (4) is made of the following materials: metal, alloy, aluminium, copper, steel (carbon steel), zinc, brass, nickel, iron, tin, bronze, carbon (in particular carbon or graphite or carbon fiber). or carbon nanotubes). Any of claims 1 to 3, characterized in that the second end of the at least one conductive element (4) is located at a greater depth in the earth than the depth of the first end. Equipment described in paragraph 1. 4. A device according to claim 1, characterized in that the second end of the at least one conductive element (4) is located at a depth corresponding to the depth of half the height of the tank (2). Equipment described in any one of the above. 6. Installation according to any one of claims 1 to 5, characterized in that the tank is buried to a depth (P) of between 50 cm and 10 m. The cryogenic tank (2) is of horizontal type, i.e. of elongated shape with a horizontal longitudinal axis, and the equipment comprises at least one conductive element distributed along the longitudinal direction of the tank (2). The equipment according to any one of claims 1 to 6, characterized in that it comprises (4).

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